Elsevier

Surgery

Volume 156, Issue 5, November 2014, Pages 1153-1156
Surgery

Endocrine
Thyrotoxicosis does not protect against incidental papillary thyroid cancer

https://doi.org/10.1016/j.surg.2014.04.025Get rights and content

Background

Thyroid cancer is the 10th most commonly diagnosed cancer in Australia, and many studies have linked thyroid-stimulating hormone (TSH) and papillary thyroid cancer (PTC). Low TSH is thought to be protective against thyroid cancer. Our aim was to evaluate the relationship between thyrotoxicosis, in particular Graves' disease, and the incidence of incidental PTC.

Methods

After ethics approval, a review of the thyroid database at Monash University Endocrine Surgery Unit was performed. Data was obtained for the period September 1994 to August 2012 and identified those patients who underwent total thyroidectomy (n = 1,898). Those patients with known or suspected malignancy were excluded from the study (n = 390). The remaining patients (n = 1,508) were divided into 3 groups: Graves' disease (n = 250), toxic multinodular goiter (MNG; n = 295), and nontoxic MNG (n = 963) based on indication for surgery and thyroid status. Data were analyzed for the presence of malignancy in each group.

Results

Of the 1,508 patients included in the study, 96 (6.4%) had thyroid cancer, and the incidence of PTC was similar between the 3 groups. There were 16 cases (6.4%) in the Graves' group, 48 cases (5%) in the nontoxic MNG group, and 20 cases (6.8%) in the toxic MNG group (P = .41).

Conclusion

The incidence of malignancy, particularly PTC, is similar in patients with Graves' disease, toxic MNG, and nontoxic MNG. This study demonstrates no protective effect of thyrotoxicosis on the incidence of incidental thyroid cancer.

Section snippets

Methods

After approval by the hospital research and ethics committee, a review of the thyroid database of the Monash University Endocrine Surgery Unit was performed. Data were obtained for the period September 1994 to August 2012. We identified those patients who underwent total thyroidectomy (n = 1,898), including patient demographics, thyroid status (thyrotoxic, euthyroid, or hypothyroid), and results of fine needle aspiration (FNA) cytology and histopathology. Thyrotoxicosis was defined by the

Results

Of the 1,508 patients included in the study, 96 (6.4%) had thyroid cancer. The mean age was 54.5 ± 15.6 years and the majority of patients were female (82.4%). The age of patients with Graves' disease was younger than patients with nontoxic and toxic MNG (39.8 ± 12.7 vs 56.7 ± 14.4 and 59.7 ± 14.1 years, respectively; P < .0001). There was a female predominance across all study groups, however, there were greater numbers of female patients in the Graves' group compared with the nontoxic MNG and

Discussion

Graves' disease, toxic MNG, and toxic adenomas are the most common causes of hyperthyroidism, and total thyroidectomy is the standard surgical treatment for patients with both bilateral benign MNG and Graves' disease.6, 10

Many studies have linked TSH and PTC. Boelaert et al7 reported that serum TSH is an independent predictor of malignancy in thyroid nodules and that the risk of malignancy rises in parallel with serum TSH, even for values in the normal range. Fiore et al8 conducted a study of

References (14)

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    The authors concluded there was no association between TSH and the incidence of papillary cancer. In another study, the rates of incidental thyroid cancer were 6.4% in Graves’, 6.8% in TMNG, and 5% in patients with multinodular goiter, suggesting that hyperthyroidism does not offer protection against papillary thyroid cancer in the extranodular thyroid tissue.22 In a frequently cited study by Fiore et al3, the prevalence of papillary thyroid cancer in patients with TSH <0.4 μU/mL was significantly less than in patients with no evidence of thyroid autonomy; this finding was interpreted because thyroid autonomy might play a protective role against the development of papillary thyroid cancer in the extranodular thyroid tissue.

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